According to a Senior Executive Intelligence Brief titled, ‘Terrorism: Bin Ladin Determined to Strike in the US’ on August 7, 2001: “Al-Qa’ida members, including some US citizens, have resided in or traveled to the US for years, and the group apparently maintains a support structure here. Two al-Qa’ida members found guilty in the conspiracy to bomb the US Embassies in East Africa were US citizens, and a senior Egyptian Islamic Jihad member lived in California in the mid-1990s.
– CIA, “Terrorism: Bin Ladin Determined to Strike in the US,” (Senior Executive Intelligence Brief), The Central Intelligence Agency’s 9/11 File:, The National Security Archive, Aug. 7, 2001